Unit-II Basic Mechanical Engineering.pptx

mechanical

1. BASIC MECHANICAL ENGINEERING Dr. G.Praveen Kumar Assistant Professor Department of Mechanical Engineering Unit-II MANUFACTURING PROCESSES

2. Course Outcomes: CO1: Understand the different manufacturing processes. CO2: Explain the basics of thermal engineering and its applications. CO3: Describe the working of different mechanical power transmission systems and power plants. CO4: Describe the basics of robotics and its applications.

3. BASIC MECHANICAL ENGINEERING Unit-II Manufacturing Processes: Principles of Casting, Forming, joining processes, Machining, Introduction to CNC machines, 3D printing, and Smart manufacturing. T hermal Engineering – working principle of Boilers, Otto cycle, Diesel cycle, Refrigeration and air-conditioning cycles, IC engines, 2-Stroke and 4-Stroke engines, SI/CI Engines, Components of Electric and Hybrid Vehicles.

4. Manufacturing Manufacturing basically implies making of goods or articles and providing services to meet the needs of mankind. Manufacturing process Manufacturing is the process of turning raw materials or parts into finished goods through the use of tools, human labor, machinery, and chemical processing.

5. Classification of manufacturing processes

6. Principles of Casting The casting process is the manufacturing process in which molten material such as metal is poured into the casting cavity or mold of the desired shape and allowed to harden or solidify within the mold , after solidification the casting is taken out by ejecting or by breaking the mold.

7. Casting Terminology • Pattern : An approximate duplicate or true replica of required product of casting Flask/Box: The rigid metal or a wooden frame that holds the moulding material Cope: Top half of the moulding box Drag: Bottom half of the moulding box Core: As and shape that is inserted into a mould to produce internal features of a casting such as holes. Gating System: Channels used to deliver the molten metal to the mould cavity Sprue: The vertical passage in the gating system Runner: The horizontal channel of the gating system Gate: Channel which connects runner and mould Riser : A vertical opening in the mould Act as a vent for gases Helps to confirm that the mould is completely filled Act as a reservoir of molten metal to feed and compensate for shrinkage during solidification of a casting

8. Have you seen any similar process before? What do we control? Size & shape of cavity and mold Mixture composition Temperature Cooling time Carefully remove it

9. Basic steps in Casting Pattern making Mold making Melting of metal and pouring Cooling and solidification of metal Cleaning of casting and inspection

10. Basic Casting Process

11. Basic Casting Process

12. Advantages Product can be cast as one piece and hence the metal joining process is eliminated. Very heavy and bulky parts can be manufactured Metals difficult to be shaped by other manufacturing processes may be cast ( eg : Cast Iron) Casting can be employed for mass production as well as for batch production . Complex shapes can be manufactured

13. Disadvantages of Casting Casting process is a labour intensive process Not possible for high melting point metals Dimensional accuracy, surface finish and the amount of defects depends on the casting process Allowances required.

14. Applications Transportation vehicles(eg.:engines) Machine tool structures. Turbine vanes Mill housing Valves Sanitary fittings Agricultural parts Construction &atomic energy applications.

15. Types of the casting process: Shell Casting Investment Casting Full Molding CO2 Molding Sand Casting True Centrifugal Casting Gravity Die Casting Pressure Die Casting Hot Chamber Die Casting Cold Chamber Die Casting and Slush Casting

16. Forming Forming is a mechanical process used in manufacturing industries wherein materials (mostly metals) undergo plastic deformations and acquire required shapes and sizes by application of suitable stresses such as compression, shear and tension.

17. Types The type of Forming Operations is as follows Rolling Forging Extrusion Wire Drawing Roll forming Stamping

18. Rolling

19. Rolling Roll forming is a continuous process which converts sheet metal into an required shape using consecutive sets of mated rolls, each of which makes only incremental changes in the form . The sum of these small changes in form is a complex profile. The Forming Process.

20. Forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces . The blows are delivered with a hammer or a die . Forging is often classified according to the temperature at which it is performed: cold forging, warm forging, or hot forging .

21. Extrusion Extrusion is a metal forming process in which metal or work piece is forced to flow through a die to reduce its cross section or convert it into desire shape . This process is extensively used in pipes and steel rods manufacturing. The force used to extrude the work piece is compressive in nature.

22. Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s). Wire Drawing

23. Roll forming Roll forming is a continuous process which converts sheet metal into an engineered shape using consecutive sets of mated rolls, each of which makes only incremental changes in the form. The sum of these small changes in form is a complex profile. The Forming Process.

24. Stamping Stamping is the process of placing flat sheet metal in either blank or coil form into a stamping press where a tool and die surface forms the metal into a net shape.

25. Welding processes Welding is a process of joining similar or dissimilar metals by application of heat with or without application of pressure and addition of filler material OR Welding is defined as an localized coalescence of metals, where in coalescence is obtained by heating to suitable temperature, with or without the application of pressure and with or without the use of filler metal.

26. Applications

27. TYPES OF WELDING : Fusion Welding or Non-Pressure Welding: The material at the joint is heated to a molten state and allowed to solidify (Ex)- Gas welding, Arc welding Plastic Welding or Pressure Welding: The piece of metal to be joined are heated to a plastic state and forced together by external pressure (Ex) –Friction Welding

28. Classification of Welding Process

29. TYPES OF WELDING JOINTS Welded joints

30. CLASSIFICATION OF WELDING PROCESSES: Gas welding(Oxy- Acetylene) Arc welding(Metal Arc) Resistance welding Solid state welding Thermo-chemical welding

31. Gas Welding: Gas Welding is a fusion welding process, in which the heat for welding is obtained by the combustion of oxygen and fuel the gas may be acetylene ,hydrogen or propene . Types: Oxy- Acetylene Air -Acetylene Oxy-Hydrogen Oxy-Fuel

32. Oxy-Acetylene Welding: When a combination of Oxygen and acetylene is used in correct proportions to produce an Intense gas flame, the process is known as oxy-acetylene welding.

33. Equipment : (Red)

34. Gas Welding Equipment : 1. Gas Cylinders Pressure- Oxygen – 125 kg/cm2 Acetylene – 16 kg/cm2 2. Regulators Working pressure of oxygen 1 kg/cm2 Working pressure of acetylene 0.15 kg/cm2 Working pressure varies depends upon the thickness of the work pieces welded. 3. Pressure Gauges 4. Hoses 5. Welding torch 6. Check valve 7. Non return valve

35. Neutral Flame: Carburizing Flame: Oxidizing Flame: There are three basic flame types: Neutral Flame (balanced) Oxidizing (excess oxygen) and Carburizing (excess acetylene) Types of flames in gas welding

36. Advantages: Portable and most versatile process. Better control over the temperature. Suitable to weld dissimilar matter. Low cost & maintenance. Disadvantages: Not suitable for heavy section. Less working temperature of gas flame. Slow rate of heating.

37. Arc Welding: “Arc welding is a fusion welding process in which the heat required to fuse the metal is obtain from the electric arc between the base metal and an electrode. Types: Metal Arc Welding Submerged Arc Welding Tungsten Inert Gas Welding Metal Inert Gas Welding

38. Equipment: A welding generator (D.C.) or Transformer (A.C.) Two cables- one for work and one for electrode Electrode holder Electrode Protective shield Gloves Wire brush Chipping hammer Goggles

39. Metal Arc Welding : Uses an electric arc to coalesce metals Arc welding is the most common method of welding metals Electricity travels from electrode to base metal to ground

40. ARC WELDING The arc welding is a fusion welding process in which the heat required to fuse the metal is obtained from an electric arc between the base metal and an electrode. The electric arc is produced when two conductors are touches together and then separated by a small gap of 2 to 4 mm , such that the current continues to flow, through the air. The temperature produced by the electric arc is about 4000°C to 6000°C. 47

41. Effects of Polarity The process may use direct current electrode positive, direct current electrode negative or alternating current. The chart above indicates the operating characteristics of each of these current types. DCEN or “ straight polarity ” is used for welding most materials other than aluminum. The electrode tip geometry is generally a sharp point with a small blunted end since most of heat balance is on the melting of the base material. DCEP or “ reverse polarity ” is rarely used since it results in low penetration. Also, the constant bombardment of the tungsten electrode by electrons in the DCEP mode degrades the electrode. Alternating current is used primarily to weld aluminum, which has a tenacious oxide surface layer. Although the diagram above states that there is a 50% cycle from DCEN to DCEP, it is possible through solid-state electronics to vary the amount of time at each polarity and also the current at each polarity.

42. Advantages and Disadvantages of Arc Welding Advantages Most efficient way to join metals Lowest-cost joining method Affords lighter weight through better utilization of materials Joins all commercial metals Provides design flexibility Disadvantages Manually applied, therefore high labor cost. Need high energy causing danger Not convenient for disassembly. Defects are hard to detect at joints.

43. Applications: It is used in the manufacture of automobile bodies. Aircraft Frames Railway Wagons Machine Frames Structural works, tanks, furniture, boilers, general repair work and ship building etc.

44. Joining processes Brazing vs Soldering If the metal bonding process uses a filler metal that melts below 450°C the bonding process is defined as soldering . However, if the filler metal melts above 450°C then the bonding process is defined as brazing.

45. Joining processes

46. Joining processes Brazing, Process For Joining Two Pieces Of Metal That Involves The Application Of Heat And The Addition Of A Filler Metal. This Filler Metal , Which Has A Lower Melting Point Than The Metals To Be Joined, Is Either Pre-placed Or Fed Into The Joint As The Parts Are Heated.

47. Machining

48. How Do We Use To Cut An Apple ?

49. Which Tool?

50. Tools Knife is Harder Knife is Sharper It is used to cut, with ease i.e., Approach Angle.

51. What Do We Use To Cut with Steel or Cast Iron or Stainless Steel ?

52. What is Common in this Process? Turning Milling Drilling Grinding These Op e ra t i o ns have material being removed

53. Application of Manufacturing Processes

54. Application of Manufacturing Processes

55. Machining: The Machining Process can be classified into: Chip Removal Process Non-Chip Removal Process (Chip less Process)

56. Machining In Machining processes in which raw material is cut into a desired final shape and size by a controlled material-removal process.  Example: Turning, Drilling, Milling etc. Metal cutting  is “the process of removing unwanted material in the form of chips , from a block of metal, using cutting tool”.

57. Chip Removal Process: In chip removal process the layers of metal from the parent metal (work piece) separated in the form of  chips  to obtain the required dimension and shape. In this process, a compressive force is applied to shear off the material in the small pieces known as  chips .

58. Chip Removal Process: Turning Drilling Milling Shaping Slotting Grinding Honing The various chip removal processes are as follows:

59. Turning: Turning is the machining operation that produces cylindrical parts. In Turning a cutting tool with a single cutting edge is used to remove material from a rotating work piece to generate cylindrical shape.

60. Drilling Drilling is a cutting process that uses a  drill bit to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool , often multi-point .

61. Boring: Boring is the process of enlarging a hole that has already been drilled by means of a single-point cutting tool .

62. Milling: Milling is a cutting process that uses rotary milling cutters to remove material by advancing the cutter into a work piece.

63. Shaping, planning and slotting: Shaping, planning and slotting can be defined as the process of removing metal from a surface in horizontal, vertical and inclined position to produce a flat or plane surface , slots and grooves by means of a relative reciprocating motion between the tool and work piece.

64. Abrasive machining: Abrasive machining is a machining process where material is removed from a work piece by using  abrasive particles.  Abrasive Machining Process can be divided into 2-categories. Grinding , Honing Bonded abrasive process (or) Fixed Loose abrasive process Polishing, Lapping

65. Grinding: Grinding is an abrasive machining process that uses a grinding wheel  as the cutting tool.  Grinding is used to finish work pieces that must show high surface quality and high accuracy of shape and dimension .

66. Honing: Honing is an abrasive machining process that produces a precision surface on a metal work piece by scrubbing an abrasive grinding stone or grinding wheel against it along a controlled path. 

67. Lapping: Lapping is a machining process in which two surfaces are rubbed together with an abrasive between them , by hand movement or using a machine. 

68. Non-Chip Removal Process (Chip less Process): Required form and dimension obtained by without removing material from work pieces. Force is applied to change the shape of the material. Forging Rolling Spinning Stamping and Embossing etc..

69. Introduction to CNC machines Computer numerical control (CNC) is a manufacturing method that uses preprogrammed computer software to automate the control, movement, and precision of machine tools . CNC is commonly used in manufacturing for machining metal and plastic parts. CNC uses a dedicated microcomputer as the machine control unit . The computer software is embedded inside the tools. The tools are operated by precisely programmed commands encoded on a storage medium. CNC is used to operate tools such as: Drills, Lathes, Mills, Grinders, Routers, 3D printers. CNC is most effective for: High feature accuracy Increased productivity Higher quality finishes Cutting intricate details Machining complex shapes

70. Servo motors Display unit Slides Controller Automatic tool exchanger Spindle CNC machines

71. The benefits of CNC are high accuracy in manufacturing, short production time, greater manufacturing flexibility, simpler fixturing, contour machining (2 to 5 -axis machining), reduced human error. The drawbacks include high cost, maintenance, and the requirement of a skilled part programmer. Advantages and Limitations

72. 3D printing

73. 3. 3D Printing To produce a part using 3D printing technique.

74. Distinction between AM & CNC machining Subtractive vs Additive Manufacturing

75. Additive Manufacturing – Layer Manufacturing Additive manufacturing, also known as 3D printing, rapid prototyping or free form fabrication, is ‘the process of joining materials to make objects from 3D model data , usually layer upon layer , as opposed to subtractive manufacturing methodologies’ such as machining. CAD image of a teacup with further images showing the effects of building using different layer thicknesses 3D Printing

76. The Generic AM Process Generic process of CAD to part, showing all 8 stages

77. Step 1: Produce a 3D model using computer aided design (CAD) software. EX: Solid works, Creo , Catia and many more. Step 2: Convert CAD file in to . stl ( StereoLithography ) format. Step 3: Slicing of the CAD model into horizontal layers (Cura,Slic3r…) Step 4 :The slicer software convert . stl file into G code which is understand by 3Dprinter. Step 5 :G –Code file uploaded in to 3D printing machine Step 6:According to G-code instructions 3D printer start printing layer by layer form a material which after become diffused together to form final object Working steps of 3D Printig

78. [2] Types of 3D Printing method Fused deposition method Laminated Object Manufacturing Stereolithographic Selective Laser Sintering (SLS). Selective Laser Melting (SLM). Types 3D Printing techniques

79. Advantages of AM Elimination of design constraints Allow parts to be produced with complex geometry with no additional costs related to complexity Build speed; reduction of lead time Flexibility in design No expensive tooling requirements Dimensional accuracy Wide range of materials (polymers, metals, ceramics) Well suited to the manufacture of high value replacement and repair parts Green manufacturing, clean, minimal waste

80. AM Applications

81. AM Applications Functional models Pattern for investment and vacuum casting Medical models Art models Engineering analysis models Rapid tooling New materials development Bi-metallic parts Re-manufacturing. Application examples for Aerospace, defence, automobile, Bio-medical and general engineering industries

82. AM Applications The Use of AM to Support Medical Applications A CT (Computerized Tomography) scanner with sliced images and a 3D image created using this technology

83. AM Applications The Use of AM to Support Medical Applications Surgical and diagnostic aids: Human models Prosthetics development Manufacturing of medically related products Tissue Engineering 3DP used to make a skull with vascular tracks in a darker colour A bone tumour highlighted using ABS Objet Connex process showing vascularity inside a human organ

84. AM Applications The Use of AM to Support Medical Applications Surgical and diagnostic aids: Human models Prosthetics development Manufacturing of medically related products: hearing aids Tissue Engineering: The ultimate in fabrication of medical implants would be the direct fabrication of replacement body parts

85. AM Applications Perfume bottles with different capacity Cast metal (left) and RP pattern for sand casting (Courtesy of Helysis Inc.) Investment casting of fan impeller from RP pattern Polycarbonate investment-casting pattern (right) and the steel air inlet housing (right) for a jet turbine engine (Courtesy DTM Corporation) SLA model of a patient’s facial details

86. Smart Manufacturing Smart manufacturing is a technology-driven approach that uses internet-connected machinery to monitor the production process. The goal of smart manufacturing is to: Identify opportunities for automating operations Use data analytics to improve manufacturing performance Minimize costs and maximize productivity Optimize the energy and workforce required

87. Smart manufacturing uses a combination of technologies and solutions, including: Artificial intelligence (AI) Robotics Cybersecurity Industrial Internet of Things ( IIoT ) Blockchain Smart manufacturing uses automation, big data analytics, and computerized controls to optimize manufacturing procedures. It can improve manufacturing efficiencies, machine configuration, predictive maintenance, and fault analysis. Smart manufacturing can help the industry create a level playing field where large companies can thrive and SMEs who are given digital resources are not left behind. SMART MANUFACTURING

88. BASIC MECHANICAL ENGINEERING Chapter-2 : Thermal Engineering. Thermal Engineering – working principle of Boilers, Otto cycle, Diesel cycle, Refrigeration and air-conditioning cycles, IC engines, 2-Stroke and 4-Stroke engines, SI/CI Engines, Components of Electric and Hybrid Vehicles .

89. Working Principle of Boiler Hot gases are produced by burning fuel in the furnace. These hot gases are made to come in contact with the water vessel where the heat transfer takes place between the water and the steam. Therefore, the basic principle of the boiler is to  convert water into steam by using heat energy . Working Principle boiler

90. Boilers Fire tube Boiler Water tube Boiler

91. Fire Tube (vs) Water tube boiler S.No Fire tube boiler Water tube boiler 1 Hot flue gases are passed through the one or more tubes that heat the water in a container Water is passed through the tubes which is heated by hot gases 2 initially, it takes time to start steam generation after firing the boiler It takes less time for steam generation after firing the boiler 3 rate of steam generation is lower rate of steam generation is higher 4 This boiler generator low-pressure steam up to 20 bar. This boiler generates high-pressure steam up to 200 bar. 5 Suitable for heating in chemical processes and also used as process steam Suitable for high capacity power generation 6 It has less risk of accidents Higher risk of an accident because of higher operating pressure 7 The initial cost is less Higher initial cost 8 The size of the boiler is larger for the same rate of steam generation. the size of the boiler is small as compared to fire tube boiler for the same rate of steam generation 9 It takes more floor area It takes less floor area 10 it requires less skilled operators for its operation It requires a skilled operator for its operation 11 The rate of heat transfer is slower hence evaporation rate is lower The rate of heat transfer is faster hence it gives a higher evaporation rate 12 The cleaning of boiler is difficult It is easy to clean this type of boiler 13 Only particular fuel has to use. As it is externally fired any available fuel for the furnace can be used 14 transportation and installation is difficult because of the large size of the shell transportation and installation is easy as it can be dismantled in number of parts 15 The maintenance is difficult in this type of boiler It is easy for maintenance 16 Less efficient compared to water tube boiler It is a highly efficient boiler 17 Example: Cochran boiler Example: Babcock and Wilcox boiler, Lamont boiler

92. INTERNAL COMBUSTION ENGINES An internal combustion engine (ICE or IC engine) is  a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit . What is the working principle of IC engine? Internal Combustion engine consists of a fixed cylinder and a moving piston. The expanding combustion gases push the piston, which in turn rotates the crankshaft. Ultimately, through a system of gears in the powertrain, this motion drives the vehicle's wheels

93. INTERNAL COMBUSTION ENGINES Classification of IC Engines: The IC engines are classified based on the following parameters.  According to the type of fuel used ( i ) Petrol Engine (ii) Diesel Engine (iii) Gas Engine  According to the method of Ignition ( i ) Spark Ignition (SI) Engine (ii) Compression Ignition (CI) Engine  According to the number of strokes per cycle of operation ( i ) Two stroke Engine (ii) Four stroke Engine  According to the thermodynamic cycle ( i ) Otto Cycle (ii) Diesel Cycle (iii) Dual Combustion cycle  According to the number of cylinders used (i) Single cylinder engines (ii) Multi cylinder engines  According to the type of cooling system ( i ) Air cooled engine (ii) Water Cooled engine

94. 2 Stroke Engine

95. 2 stroke engine Compression stroke In the compression stroke, the inlet port will be opened making the air and fuel mixture enter the compression chamber. The piston will moves to top position Here when the piston moves upwards, the mixture of fuel and air compression starts. At the end of this process, a spark will ignite the fuel and begin the power stroke process. Power stroke In the power stroke, the fuel will be burnt and the gas will be exerted at high pressure causing the piston to move downwards. The heat which is wasted will be emitted from the exhaust valve.

96. 4 Stroke Engine

97. The four piston strokes are Intake Compression Ignition Exhaust

98. The four piston strokes Intake Compression Ignition Exhaust

99. The four piston strokes are Intake In this intake stroke, in the cylinder which is fixed part, the piston will moves from top position (TDC top dead center) to down position (BDC bottom dead center) Intake value will be open Exhaust value will be closed The piston which moves downwards will create a vacuum that sucks the fuel and air inside the engine through the intake valve which is opened in this process. Compression stroke: In this compression stroke, the piston will now moves from down position (bottom dead center BDC) to top position (TDC top dead center) Intake value will be closed Exhaust value will be closed The piston which moves upwards will compress the sucked fuel and air (in the intake process) inside the combustion chamber. In this process, a spark of fire will be ignited.

100. The four piston strokes are Power stroke: The spark fire which happens in the compression stroke will ignite the air and fuel. This ignition will force the piston to move back downwards, making the vehicle wheel to rotate forward. In this power stroke, the piston will now moves from top position (top dead center TDC) to bottom position (BDC bottom dead center) Intake value will be closed Exhaust value will be closed. Exhaust stroke In this exhaust stroke, the piston will now moves from down position (bottom dead center BDC) to top position (TDC top dead center) Intake value will be closed Exhaust value will be opened This is the final process where the gas will be released through the exhaust valve of the cylinder. After completion of this process the piston is now ready for the intake process.

101. Differences/Difference Between Two Stroke And Four Stock Engine Four stroke engine Two stroke engine In a four stroke engine to complete the four stroke process it requires two complete revolutions. In a two stroke engine to complete the two stroke process it requires one complete revolution. The four piston strokes are * Intake * Compression * Ignition * Exhaust The two stroke are Compression stroke Power stroke Inlet valve and exhaust valve Inlet port and exhaust port Combustion of fuel is full Combustion of fuel is not full High thermal efficiency and less smoke Low thermal efficiency and high smoke Exhaust gas removed easily Exhaust gas removed is difficult Engine weight is high for per hp because the flywheel is high Engine weight is comparatively less for per hp Low torque High torque Tough to manufacture and engines are costlier due to lubrication and valve. Simple to manufacture and engines are cheap More wear and tear happens because of poor lubrication Wear and tear are less Speed can be varied from high to low High speed engine are mostly available Operates in only one direction Operates in both direction (anti clockwise direction and clockwise direction)

102. Application of two stroke and four stroke engine Four stroke engine Two stroke engine Automobiles like cars, trucks and some bikes which uses fuel like gasoline, aircraft Chainsaws, motorcycles, racing applications, weed eaters, military tanks, ships. In four stroke engine are lubricated by oil so not flexible in cold temperature In a two stroke oil sump is not in design hence it can be easily started in cold conditions. High expensive and low noisy Less expensive and more noisy

103. Otto cycle The Otto cycle, which was first proposed by a Frenchman, Beau de Rochas in 1862, was first used on an engine built by a German, Nicholas A. Otto, in 1876 . The cycle is also called a constant volume or explosion cycle . This is the equivalent air cycle for reciprocating piston engines using spark ignition. The following is the P-V diagram which represents all the processes. T1—Temperature of the charge at point 1 T2—Temperature of the charge at point 2 V1—Volume of the charge at point 1 V2—Volume of the charge at point 2 ϒ – Compression ration ( V2/V1) At the start of the cycle, the cylinder contains a mass M of air at the pressure and volume indicated at point 1. The piston is at its lowest position. It moves upward and the gas is compressed isentropically to point 2. At this point, heat is added at constant volume which raises the pressure to point 3. The high-pressure charge now expands isentropically , pushing the piston down on its expansion stroke to point 4 where the charge rejects heat at constant volume to the initial state, point 1.

104. Diesel cycle Diesel Cycle This cycle, proposed by a German engineer, Dr. Rudolph Diesel to describe the processes of diesel engine, is also called the constant pressure cycle. The P-V diagram is shown in Fig. Process 1-2: (Adiabatic compression ) At condition 1, the piston is at lower end position and air filled in the cylinder. Then the piston is moved from lower end position to upper end position 2 there by adiabatically compressed Process 2-3: Constant pressure heat addition Here in this process, some heat is added to the compressed air at constant pressure. Process 3-4 : Adiabatic expansion In this process, air at condition of high pressure and temperature expands adiabatically on its own and does mechanical work by pushing the piston to lower end positions. Process 4-1 : ( Constant volume heat rejection ) So in the process 4-1, a heat sink comes in contact with cylinder head and air rejects its heat at constant volume. Its pressure and temperature drops to the same initial values P 1 and T 1 .

105. CI/SI Engines S.No Diesel engine Petrol engine It has got no carburetor, ignition coil and spark plug. It has got carburetor, ignition coil & spark plug. 2 Its compression ratio varies from 14:1 to 22:1 Its compression ratio varies from 5:1 to 8:1. 3 It uses diesel oil as fuel It uses petrol (gasoline) or power kerosine as fuel. 4 Only air is sucked in cylinder in suction stroke. Mixture of fuel and air is sucked in the cylinder in suction stroke. 5 It has got ‘fuel injection pump’ and injector It has got no fuel injection pump and injector, instead it has got carburetor and ignition coil. 6 Fuel is injected in combustion chamber where burning of fuel takes places due to heat of compression. Air fuel mixture is compressed in the combustion chamber when it is ignited by an electric spark. 7 Thermal efficiency varies from 32 to 38% Thermal efficiency varies from 25 to 32% 8 Engine weight per horse-power is high. Engine weight per horsepower is comparatively low. 9 Operating cost is low. Operating cost is high. 10 Compression pressure inside the cylinder varies from 35 to 45 kg/cm2 and temperature is about 500°C. Compression pressure varies from 6 to 10 kg/cm2 and temperature is above 260°C.

106. Electric and Hybrid Vehicles Battery Pack : The main function of this component is to store and supply Direct current to the inverter. Further, the power generated will be used to drive the traction motor. When the controller sends a signal, the traction battery will immediately work by transferring electric current to drive the traction motor. These vehicles charge their batteries with electricity rather than utilizing fossil fuels like petrol or diesel. Electrical vehicles play a vital role in fighting climatic change throughout the world by lowering the emissions and decreasing the reliance on fossil fuels. Electric vehicles consist of an electric motor that is powered by a battery pack. Power Converter: Inverter is a component that functions to convert DC current into AC current or alternating current. The resulting current will then be used to drive or rotate the traction motor. This current is used to recharge the battery.

107. Electric and Hybrid Vehicles Transmission: The transmission transfers mechanical power from the electric traction motor to drive the wheels. Auxiliary Supply: It supply the power to run vehicle accessories and recharge the auxiliary battery. Thermal System –Cooling: This system maintains a proper operating temperature range of the engine, electric motor, power electronics, and other components. Controller: It acts as a regulator of electrical energy from batteries and inverters that will be distributed to the electric motors. This controls the speed of the electric traction motor and the torque it produces. Electric Motor: This receives the power from the traction battery and turns the wheels of the motor. Battery Charger: It is a battery charging device which receives the power from external source and converts AC into DC and stored in the battery

108. Electric and Hybrid Vehicles Battery (auxiliary): In an electric drive vehicle, the low-voltage auxiliary battery provides electricity to start the car before the traction battery is engaged; it also powers vehicle accessories. DC/DC converter: This device converts higher-voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery. Electric traction motor: Using power from the traction battery pack, this motor drives the vehicle's wheels. Some vehicles use motor generators that perform both the drive and regeneration functions. Exhaust system: The exhaust system channels the exhaust gases from the engine out through the tailpipe. A three-way catalyst is designed to reduce engine-out emissions within the exhaust system. Fuel filler: A nozzle from a fuel dispenser attaches to the receptacle on the vehicle to fill the tank. Electric generator: Generates electricity from the rotating wheels while braking, transferring that energy back to the traction battery pack. Some vehicles use motor generators that perform both the drive and regeneration functions. ENGINE clutch Transmission Battery Driver Shaft Wheels Wheels

109. Electric and Hybrid Vehicles Fuel tank (gasoline): This tank stores gasoline on board the vehicle until it's needed by the engine. Internal combustion engine (spark-ignited): In this configuration, fuel is injected into either the intake manifold or the combustion chamber, where it is combined with air, and the air/fuel mixture is ignited by the spark from a spark plug. Thermal system (cooling): This system maintains a proper operating temperature range of the engine, electric motor, power electronics, and other components. Traction battery pack: Stores electricity for use by the electric traction motor. Transmission: The transmission transfers mechanical power from the engine and/or electric traction motor to drive the wheels. Power electronics controller: This unit manages the flow of electrical energy delivered by the traction battery, controlling the speed of the electric traction motor and the torque it produces

110. Refrigeration and Air-Conditioning cycles Refrigeration is a process of removal of heat from a space and transferring the same to the surrounding environment. It is identified that the spoilage of food and many other items reduces at a lower temperature. At a lower temperature, molecular motion slows down and the growth of bacteria that causes food spoilage also retards . Thus to preserve many types of perishable food products for a longer duration, temperature of the food products has to be maintained at low temperature.

111. Refrigeration and Air-Conditioning cycles Air Conditioning Air conditioning is the process of simultaneous control of temperature, humidity, cleanliness and air motion. Ex: Car air conditioning / Room Air conditioning Depending upon the requirement, air conditioning is divided into the summer air conditioning and the winter air conditioning . In the summer air conditioning, apart from cooling, moisture should also be removed, whereas in the winter air conditioning, space is to be heated along with the addition of moisture to the space to be conditioned. The summer air conditioning thus uses a refrigeration system and a dehumidifier. The winter air conditioning uses a heat pump and a humidifier. Further depending upon the comfort of the human beings and the control of environment for the industrial products and processes, air conditioning can also be classified as comfort air conditioning and industrial air conditioning. Comfort air conditioning deals with the air conditioning of residential buildings, offices spaces, cars, buses, trains, airplanes, etc . Industrial air conditioning includes air conditioning of the printing plants, textile plants, photographic products, computer rooms, etc.,

112. Refrigeration and Air-Conditioning cycles Simple Vapour Compression Refrigeration System It consists of the following essential parts: Compressor The low pressure and temperature vapour refrigerant from evaporator is drawn into the compressor through the inlet or suction valve A, where it is compressed to a high pressure and temperature. This high pressure and temperature vapour refrigerant is discharged into the condenser through the delivery or discharge valve B. Condenser The condenser or cooler consists of coils of pipe in which the high pressure and temperature vapour refrigerant is cooled and condensed. The refrigerant, while passing through the condenser, gives up its latent heat to the surrounding condensing medium which is normally air or water. High-pressure A B

113. Refrigeration and Air-Conditioning cycles Simple Vapour Compression Refrigeration System Receiver The condensed liquid refrigerant from the condenser is stored in a vessel known as receiver from where it is supplied to the evaporator through the expansion valve or refrigerant control valve. Expansion Valve It is also called throttle valve or refrigerant control valve. The function of the expansion valve is to allow the liquid refrigerant under high pressure and temperature to pass at a controlled rate after reducing its pressure and temperature. Some of the liquid refrigerant evaporates as it passes through the expansion valve, but the greater portion is vaporized in the evaporator at the low pressure and temperature Evaporator An evaporator consists of coils of pipe in which the liquid- vapour . Refrigerant at low pressure and temperature is evaporated and changed into vapour refrigerant at low pressure and temperature. In evaporating, the liquid vapour refrigerant absorbs its latent heat of vaporization from the medium (air, water or brine) which is to be cooled.